Quouting from that page:
That ensures that, even if I happened to insert a literal tab in the
file by hand (or if someone else did when editing this file earlier),
those tabs get expanded to spaces when I save.

If you are using a source management system, pretty much *any* source
management system, doing this will cause all the lines to be "rewritten"
if they had tabs. The fact that this person would advocate changing
code that they didn't actually change shows a distinct lack of clue.
No engineer who works for an even semi-pro company would dream of doing
this. At BitMover, anyone who seriously advocated this for more than
a day would be fired.